The hard encryption keyboard of a bank self-service equipment bears works of inputting and encrypting a bank password of a user, and thus a working key and a master key of the bank are stored in a core processing part of the keyboard. For an unspeakable purpose, some criminals usually jimmy or poke the keyboard to steal the user password and even to decrypt the working key and master key of the bank in order to steal bank information, which threatens the security of information and money of the user and the bank directly.
The encryption keyboard is generally provided with a poking detection and protection structure and a poking detection and protection circuit. When the encryption keyboard is subjected to a physical poking, the poking detection and protection circuit outputs a self-destruction signal to realize a self-destruction function of the encryption keyboard, so as to prevent the criminals from stealing bank information.
A conventional encryption keyboard generally includes a keyboard panel, a plastic lining plate, keystrokes, water-proof silicone rubber, a main control board and a bottom board, and the above components are firmly assembled with bolts and nuts. Contact surfaces of the plastic lining plate and the water-proof silicone rubber are generally smooth flat surfaces so as to enable the plastic lining plate and the water-proof silicone rubber to abut against each other in parallel. Additionally, for the purpose of water-proof, the water-proof silicone rubber must have a certain thickness generally being 0.5 mm. However, an aggressor may easily penetrate through the water-proof silicone rubber of 0.5 mm with a heated iron wire and then lead out a conductive wire below the keystrokes so as to communicate with the encryption keyboard and thus to steal information such as user's password and bank key.